The preferred embodiment concerns a toner roller that is suitable to take up a layer of toner particles on its surface shell (generated surface) and that comprises a roller-shaped inner body. A dielectric layer is arranged on the surface shell of the inner body.
The toner roller according to the preferred embodiment is in particular used in developer stations of printers or copiers. The toner roller is, for example, used as a developer roller that is situated opposite an intermediate image carrier. The intermediate image carrier is, for example, a photoconductor belt and carries a latent charge image corresponding to an image to be printed. The latent charge image of the intermediate image carrier is inked with toner with the aid of the developer roller. For this the developer roller must carry a homogeneous layer of toner particles in operation. A voltage potential is applied to the developer roller, with the help of which the transfer of the electrically charged toner particles from an inking roller to the surface of the developer roller and the transfer from this developer roller to the intermediate image carrier is assisted. The toner roller according to the preferred embodiment can also be used as a cleaning roller, for example, with the help of which toner and carrier particles that are not transferred from the developer roller to the intermediate image carrier are cleaned from the developer roller.
Depending on the use, the toner roller must satisfy different requirements. Given a developer roller, the discharging and charging of the developer roller must occur in short time spans, for example. In contrast to this, given a cleaning roller the discharge should occur as slowly as possible so that as many toner particles as possible can be cleaned off the developer roller. The developer roller must also be provided such that the correct amount of toner is applied to it. If too few or too many toner particles are applied on the developer roller, a stable, homogeneous development of the latent charge image of the intermediate image carrier is not ensured. Furthermore, the developer roller must have a sufficiently high breakdown resistance.
In the document DE 10 2008 050 745.8 (not published before the filing of the instant corresponding German Priority Document), a toner roller is proposed that is suitable to take up a layer with toner particles on its surface shell. The toner roller has a base body made of a material whose specific resistance >10−4 Ω/cm and a modulus of elasticity of which is greater than 50 kN/mm2. An electrically conductive layer that is charged with an electrical potential is arranged on the surface of the base body.
A method for treating the surface of a toner-transporting roller is known from the document US 2007223973 A1. The surface of the roller is coated with a ceramic layer that is subsequently exposed with a grit (shot), in particular with glass spheres. Scaling, oxidation layers and soiling of the ceramic layer are removed via this method, and this ceramic layer is additionally re-pressed.